It just keeps getting better and better. The convertible SLS AMG Roadster is the second car to be developed independently by AMG. Currently undergoing testing in Stuttgart, the roadster vehicles are minimally disguised as they cover their test routes. The proportions speak for themselves with a long hood, large wheels and a short rear unified by breathtaking design. There are still six months to go before the world premiere at the International Automobile Show in Frankfurt in September 2011.
The personnel responsible at AMG have already completed most of the work involved since the Coupé and Roadster were created in parallel. The development and testing of a new AMG high-performance car is based on the digital prototype (DPT). Extensive investigations help to achieve specific objectives such as the bodyshell design, weight distribution, engine position, center of gravity or axle design. The very latest simulation programs allow engineers to test handling dynamics, aerodynamics, ergonomics, crash behavior and production process. The digital prototype is therefore a complete, virtual automobile.
In order to achieve handling dynamics identical to the Coupé – without a fixed roof – the Roadster has two features designed to increase the rigidity of the bodyshell: the cross-member carrying the dashboard has additional supporting struts at the windshield frame and at the center tunnel, and a structure between the soft top and the tank stiffens the rear axle. These features prevent unwanted vibrations from the start and dispose of additional weight-increasing vibration dampers often employed by competitors. The bodyshell of the Roadster tips the scales at only 536 pounds – which is comparable to the low, 531 pounds of the SLS AMG Coupes bodyshell.
Without a fixed roof and gullwing doors, the convertible SLS AMG has a reinforcing cross-member behind the seats which supports the fixed rollover protection system. The 250-watt subwoofer of the Bang & Olufsen BeoSound AMG high-end sound system is located in the cross-member rather than the parcel shelf of the Coupe. One particular challenge was acoustic insulation of the cross-member, which acts as a subwoofer housing for the two 6.5-inch speakers connected in series. Numerous improvements became necessary before the required listening pleasure was met. It was only with the help of a special bulkhead within the aluminum cross-member that the system was deemed ready.
The three-layer fabric soft top of the SLS AMG Roadster, which is stored behind the seats in a Z-formation to save space, is also relevant to handling dynamics. This weight-optimized magnesium/steel/ aluminum construction provides a low center of gravity and is designed for speeds up to the maximum of 197 mph (electronically limited). Engineers stressed that whether open or closed, even at top speed there must be no intrusive flapping, booming, hissing, clattering, whistling or howling. Likewise the plexi-glass windstop and the paneling in the interior, on the soft top and along the beltline must be vibration-free. These precisely defined tests were conducted on the high-speed tracks in Papenburg, Nardo (Italy) and Idiada (Spain).
